Hello alexM, and welcome to our community!
No trouble at all, we can assist with that.
The Shake you will be working on is an RS4D (RS4D | Strong Motion Seismograph), as you can see from these two labels:
To answer your questions, if the Shake is still turned on, then yes, it will still be recording data up to the set limit (that I imagine the previous person who worked on it adjusted to their needs) in the Shake configuration page (an example below):
When this limit (in days) is reached, the older data is overwritten by the most recent data. When you get there, I have listed what is required to connect to the Shake in your other topic here: USB SD card device - #2 by Stormchaser
The black antenna connected to it would be a GPS module, which would keep the time up-to-date with the worldwide atomic clocks and ensure that all data the Shake has recorded is synchronized.
To connect to the Shake you will simply need a laptop with a working Ethernet (LAN) port, where you can connect the white cable that you can see in the box (coming out the Ethernet-labelled) connector, and then follow what is written in the link above.
For anything else, I remain available.